Improving the device performance of organic solar cells with immiscible solid additives

Morphology optimization is key for the high-performance of organic solar cells (OSCs). Herein, we develop a solid additive (i.e. uv-9) showing immiscibility with active layers for morphology control, and comprehensively study its effect on the morphology evolution and device performance of PM6:Y6 OSCs. The addition of uv-9 leads to more refined phase separation and stronger molecular packing in PM6:Y6 blend films, and improves the charge generation, exciton dissociation, charge transport and collection, which contribute to higher photocurrent and fill factor for PM6:Y6 OSCs. Consequently, the OSC device with the uv-9 solid additive exhibits an improvement in the power conversion efficiency from 16.00% to 17.18%, compared to the control device without an additive. Moreover, the generality of uv-9 as an effective solid additive has been verified by applying it to diverse OSCs. This work suggests a new class of solid additives to optimize the morphology of OSCs for high performance.